Wildcatsteve

I just got my 2016 F150, 5.0 XLT Supercab. The tire pressure sticker in front door reads 35psi. My tires read max 51 psi. They have from 40 to 44 lbs from dealership....according to the read out on my dash.

Is the max supposed to be 35 psi? Also, do I need to increase over the 35 when towing my TT?

I asked my salesman when I took it back for a cleaning why the tires had 44 lbs and the sticker reads 35......and I really don't know what he said. I think he just made something up, did not make any sense. :-)

Steve Osborne

i'll post what I have done with my 13 and now the 16....
both my truck came listed with LT tires stock 18's....
the 13 tires stamped max 50psi...door sticker said I think44 psi.....I ran 40 front and 44 rear...only added more as I loaded up more ....
the 16 is set for 40 all around for now.....
the tires are stamped with a max psi for the max load they will carry.....which for most is to much and over inflates the tires.....go by the door tag....this was fords recommended psi for the weight of the truck....if you load up add to accommodate the added weight..

Bill_The_PA

I fully agree with Steve. I too have stock LTs and I run them as per door pillar unless hauling /towing. In these situations I inflate to carry actual measured load + minimal 10% margin. All my trailers I always run them to max inflation as per the modded information on sidewall unless it is higher the rim recommend pressure.

smokeywren

No. On P-Series standard load (SL) tires, the max weight capacity is achieved at 35 PSI, but the speed rating increases with more PSI. The sidewall says 44 PSI, which will give you the speed rating on the sidewall, but the same load capacity as 35 PSIl


Study a TRA load/inflation table for your size tires and note that the max weight capacity is achieved at 35 PSI.


For example, my 2012 4x2 came with P-265/60R18. The load inflation table says:

P265/60R18 109 SL
1973 @ 26
2083 @ 29
2183 @ 32
2271 @ 35
Blank for 35, 38, 41,and 42 PSI


So even though the sidewall says 2271 max load @44 PSI, it also has 2271 max load @ 35 thru 44 PSI.
https://www.toyotires.com/tires-101/tire-load-and-inflation-tables - page 19 for size P-265/60R18, as well as P265/65R18 if your truck is a 4x4.

Assuming you don't tow at more than 65 MPH, which is probably the limit for the ST tires on your trailer, then there is no reason to inflate the P-Series truck tires to more than 35 PSI.


But do what I say, not what I do. When towing, I always pump up my P-Series rear tires to 44 PSI cold, but leave the front tires at about 35 PSI. No real reason other than I prefer the stiffer ride of the pumped-up rear tires.

SKBORDERS

Factory tire inflation pressures are set to give the best possible ride along with the best possible wear. over inflated they wear out the middle, under inflated they wear out the sides and overheat. Neither give optimum traction.

Towing tire pressures should be set so that the tread sets flat, makes full contact on the road with the load they are carrying and they don't overheat.

jadatis

already written that P-tires in SL carry their maximum load AT 35 psi for USA system , and then maximum speed you wont go over for even a minute, is 160km/99m/h .
Its all done to give the tire a deflection , at wich no part of rubber reaches a to high temperature , so it hardens ( by to many sulfurbridges made) and so damages in next bendings of that rubber in next deflections.

That is as the tiremakers determined, but to laws of nature there are some exeptions.

The Ford Explorer ( search Ford/Firestone Affaire where more then 100 people died by)had offroadlooking tires with profile blocks that cover a part of sidewall . This made lesser sidewall possible to flex , so more heatproduction if you gave it same deflection of a road-tire.

so probably your tires also are offroadlike tires , and those are give to high maximum load on sidewall for that 35 psi pressure. My estimation is to substact 20% even of maximum load given on sidewall or lower Loadindex by 8 steps. This would yustifie the 40-44 psi the tiremen did.

As late as 2006 American TRA stepped over for SL and XL P-tires to the calculation of pressure of European ETRTO, because the calculation they used for those where verry bad.
the list Smokywrenn gives of Toyo is made with that old calculation , so I checked, for 26 psi calculated with EUR calculation ( and after 2006 also USA) it would give only 1790 lbs and not the 1973 lbs given .
In the Ford/Firestone Affaire this miscalculation was not the main cource, because corrected by substacting 10% of maximum load of P-tires for SUV/MPV or whatever it called. But after FF affaire cooled down they chanched the calculation to the EUR one that had been used for decades for all kind of radial tires from SL to Trucktires.
The 10 % reduction was never done in Europe .

But your car most likely have pretty oversised tires, so if you dont go over GAWR ( Gross Axle Weight Rating) wich to law you are not allowed, an adding of 10% for R/L weightdifference would be enaugh.
Then let me calculate the pressure for that with all the reductions done , and you will have a save pressure.
My estimation , not knowing the weights , is that pressure comes to about 30 psi for fully loaded , mayby behind when towing that 35 psi, but can be wrong, so lets calculate.
Can also calculate it for your normal use, but determining the weight on seperate wheels for that , is the most tricky thing in this all.

Greatings from a Dutch Pigheaded Self declared Tirepressure-specialist.
Peter

11screw50

When inflated to the pressure on the sticker, the tires are rated to carry the maximum load (or more) that the axles are rated to carry. If you need more air in them to make them flat, you are probably overloaded.

(Seems like we've been here before doesn't it?)

Dirttracker18

Do you know if the dealer changed out the stock tires on your truck? That may explain the increased tire pressure from them.
The sticker on your door is for the stock tires that came with the truck. If they changed them to a different make, model (P vs LT) or size then the optimum pressure may have changed.

SKBORDERS

Yeah, you are correct. The maximum load of the tire @ 51 PSI is actually greater on my truck than the axle.


I always watch my tires and adjust them for wear.